Recycle spray gas-liquid contactor

Abstract

This invention relates to a novel gas-liquid contacting apparatus and method utilizing recycle spray contact trays disposed within a substantially vertical vessel. Each contact tray contains one or more housings defined by upstanding vertical wall members, said housings being open to gas flow at top and bottom. Within the housings, liquid spray is continuously generated by means of gas flowing upward past a first array of horizontally spaced-apart gas venturi-generating liquid conductors. Liquid flows from the tray floor outside the housing through the liquid conductors, is distributed into the gas, and is entrained upward as spray by the gas venturi action. Horizontally-disposed foraminous or perforated flow-restrictive elements, vertically spaced apart, mounted on top of the housings, cause the liquid spray to coalesce and regenerate at the first flow-restrictive barrier element which occupies the cross-sectional area of the vertical housing. A major portion of the gas and contained spray is then caused to flow laterally, normal to the upward gas flow direction, through the high-voidage space between the elements. The flow-restrictive elements are comprised of foraminous or perforated plates, or anisotropic material such as layered mesh. The spray issuing laterally impinges on the vessel walls and liquid therefrom drains downward or falls by gravity to the tray floor, where the process is repeated. The method of invention encompasses spray contacting with automatic and continuous recirculation of liquid spray in a controlled manner at rates that are multiples of the liquid throughput rate, and is capable of operation at high has velocities and low pressure drop.

I claim: 
     
       1. Gas-Liquid contact apparatus consisting of a vertically disposed vessel containing at least one horizontal tray, means for introducing liquid to, and removing overflow from, the tray, and at least one vertically arranged housing thereon that is open to gas flow at top and bottom, the housing enclosing a horizontally disposed array of liquid conductors in substantially parallel arrangement at the level of the tray and so spaced apart as to effect constricted venturi passages for the upward flow of the gas therebetween, said conductors having means for delivery therefrom of liquid from the tray into the gas; an disposed upon and supported on and occupying the cross-sectional area of said housing, flow-resistant elements comprises of anisotropic layered material having low flow resistance in the horizontal direction relative to the flow resistance in the vertical direction, said anisotropic layered material having edges open to the volume between the vessel and the housing. 
     
     
       2. The apparatus of claim 1 in which the flow-restrictive elements are comprised of knitted mesh layers. 
     
     
       3. The apparatus of claim 1 in which the flow-restrictive elements are comprised of layers of woven screen. 
     
     
       4. The apparatus of claim 1 in which the vertically disposed vessel contains a number of the said horizontal trays, one above the other, each having a vertical housing enclosing at the level of the tray the said liquid conductors and, supported on each vertical housing, the said flow-restrictive elements, and means for feeding liquid to each tray and removing overflow liquid from each tray. 
     
     
       5. A method of mass transfer of substances between a liquid and a gas comprising the steps of: introducing liquid at a pre-determined rate to a tray containing liquid-conducting tubes so spaced apart to induce gas venturi flow, passing a gas upward between the tubes, aspirating liquid from orifices in the tubes by gas venturi aspiration at a rate that is many time greater than the initial rate of introduction of liquid to the tray, effecting thereby a cocurrent spray of liquid in the gas; passing the gas and contained spray through a first flow-restrictive element which partially coalesces and regenerates the spray; passing the gas and regenerated spray into a relatively high-voidage volume between the first flow-restrictive element and a secondary flow-restrictive element, thereby causing the gas and spray to flow laterally through the high voidage volume between the elements; collecting spray and gas discharged from the high voidage volume and separating the spray by impingement on a plane surface and causing the liquid therefrom to recycle into cocurrent spray contact with a further quantity of the gas at a liquid rate that is many times higher than the initial pre-determined rate of liquid introduction to the tray; withdrawing so-treated liquid from ultimate contact with inflowing gas and so-treated gas from contact with inflowing liquid.